from the feeling-safer? dept

We've heard the various stories of folks getting weapons past the TSA's new scanners -- such as Adam Savage's famous video from earlier this year, or the more recent report of a guy getting past the scanners with a 6" hunting knife. Both of those stories appeared to just be about the bag scanners missing stuff on the conveyor belt. But what about the new backscanner x-ray machines? Well, Jay points us to some new research by two UCSF professors that indicates getting dangerous weapons or explosives past the new machines isn't that hard. They look at how the machines work and the various images currently out there, as well as their understanding of x-ray technology, and point out that since the x-rays need to pass through your body, if you flattened out some plastic explosives, they probably won't be noticed, or if you just put the weapon on your side the new machines probably won't spot them:

It is very likely that a large (15–20 cm in diameter), irregularly-shaped, cm-thick
pancake with beveled edges, taped to the abdomen, would be invisible to this
technology, ironically, because of its large volume, since it is easily confused with
normal anatomy. Thus, a third of a kilo of PETN, easily picked up in a competent pat
down, would be missed by backscatter "high technology". Forty grams of PETN, a
purportedly dangerous amount, would fit in a 1.25 mm-thick pancake of the
dimensions simulated here and be virtually invisible. Packed in a compact mode,
say, a 1 cm×4 cm×5 cm brick, it would be detected.

The images are very sensitive to the presence of large pieces of high Z material, e.
g., iron, but unless the spatial resolution is good, thin wires will be missed because
of partial volume effects. It is also easy to see that an object such as a wire or a boxcutter blade, taped to the side of the body, or even a small gun in the same location,
will be invisible. While there are technical means to mildly increase the conspicuity
of a thick object in air, they are ineffective for thin objects such as blades when they
are aligned close to the beam direction.

Feeling safer? Once again, this isn't to say that there shouldn't be a security screening process, but if we have to go through all this trouble, shouldn't we at least have a system that is at least somewhat effective?

from the who's-scanning-whom? dept

A few months back, we wrote about how the backscatter x-ray technology, which is now causing concern in airports for effectively showing the "naked" you to TSA staffers, was also being used in vans by law enforcement. They could drive around and see scans of what was in cars and buildings around them.

We noted at the time that 500 of these had been sold, mostly in war zones, but noted some were in use in the US. Now, there's a report that looks more deeply at the vans and the controversy surrounding them and notes that the company that makes them also appears to sell them to private individuals. Most of the reports of sales are to various government agencies, but as you dig deeper, the sales become more vague:

Other releases are more vague, however, identifying the purchasers only as "the U.S government," a "Latin American customs agency," an "international government agency," "U.S. law enforcement officials," a "South American government," a "Middle Eastern country," a "Middle Eastern government," a "Middle East government agency," a "Middle East law enforcement agency," a "South American law enforcement agency," a "new African customer," a "European Union (EU) and an Asia Pacific (APAC) client," and a "Middle Eastern customer."

Defenders of the systems basically say that people shouldn't be afraid of such things because they need to be used within the requirements of privacy laws (in the US, at least), but seem to ignore how the US government has been more or less ignoring the 4th Amendment pretty regularly lately. They also say that the technology isn't good enough to really get the "naked scans" unless you're right next to the van. Of course, since the vans are made up to look like ordinary vans, most people will have no idea if they're standing right next to one. And, on top of that, you have to assume that the scanning technology is only going to improve over time, meaning that it will be able to get much more detailed scans from a much greater distance.